WILLS CANYON stands out as a slice of the Ojai Valley as it may have looked about 175 years ago. In Thousand Oaks, you see a lot of oaks but no understory, the plants growing close to the ground at the base of shade trees.

This untouched canyon has coastal live oaks and all the understory — snowberries, Humboldt lilies, hummingbird sage — intact.

As manager of the Ventura River Preserve, which opened last December, I often hike to the oak savanna along this six-mile loop.

You leave the trailhead and walk about a mile through open terrain and then cross the Ventura River bottom, which is dry at this time of year.

(Crossing in January through May might involve some rock-hopping; it’s inadvisable after a big storm.)

Follow the well-marked trail across the river bottom and through a riparian area thick with sycamores, willow trees and mulefat.

After you go up a little hill and make a left, go about a quarter-mile and you’re in the oak savanna. The beginning of this trail can be hot and exposed, but it’s about 20 degrees cooler once you reach the trees.

Leaving the savanna, the trail climbs about 500 feet and enters the Rice Canyon drainage, which winds through dry chaparral.

For about a mile you’re on Los Padres National Forest turf. Here the trail opens and offers spectacular views toward the east and the Topatopa Mountains, a dramatic 6,700-foot formation above the Ojai Valley.

The Topas are striking, like the Rockies, with accentuated rock strata.

The mood here is serene and tranquil, a respite from the urbanized world.

Traveling east on the loop, you come back across the riverbed at a different location and follow the signs labeled Trail 2. This will take you down a little hill, and about a quarter-mile later you come to a junction.

Take the first left and stay on that course for another half a mile as you slowly curve to the right. At this point, you’re heading back to the trailhead.

The particulars

Where: Wills Canyon Trail Loop in Ventura River-Rancho El Nido Preserve, owned and managed by the Ojai Valley Land Conservancy. (Guided hikes in the preserve are listed at www.ovlc.org.)

What: A six-mile loop that crosses the Ventura River and leads through one of the last remaining oak savannas in Ventura County, then opens to chaparral and views of the nearby Topatopa range.

How: From the 101 Freeway take Highway 33 north about 11 miles. At the intersection with Highway 150, turn left. Go three blocks and turn right onto Rice Road in Meiners Oaks. Start at the Riverview Trailhead, which is across the street from a horse boarding facility.

Back story: The preserve is part of a 1,591-acre ranch that was once called El Nido, or “the nest,” in Spanish.